<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>节点</title>
</head>

<body>

    <div class="c">

        <div class="a">
            <span class="b"></span>
        </div>

    </div>

</body>

<script>
    var b = document.querySelector('.b');

    console.log(b.parentNode.parentNode);
</script>

</html>